1. Field of the Invention
The present invention relates to a self-alignment filling level detecting device, and more particular to a self-alignment filling level detecting device comprised of a reflector and a sensor detachable from each other.
2. Description of the Prior Art
Optical level detecting devices are widely used in many different fields such as petrochemical industry, foodstuff industry, iron and steel industry, cement industry, etc. to measure a filling level of raw material or liquid stored in a container.
With reference to FIG. 18, the U.S. Pat. No. 6,921,911, entitled “Method and device for optically determining a filling level in liquid-filled containers”, provides a detecting device 80 to be mounted on a wall 91 of a container. The detecting device 80 comprises a body 81 and a circuit board 82.
The body 81 has multiple stepped portions 811, which are connected by reflection faces 812, 812′. The stepped portions 811 and reflection faces 812,812′ have different diameters, wherein the stepped portion 811 at top has a greater diameter than a diameter of the stepped portion at bottom. Each reflection face 812, 812′ corresponds to an individual liquid level. Further, the bottom-most reflection faces 812′ at a lower end of the body 81 form a V-shape in cross-section.
The circuit board 82 has a light source 821 and a light sensor 822. The light source 821 emits collimated light beams to the reflection faces 812, 812′. In this example, only the bottom-most reflection face 812′ is immersed in liquid 92 while other reflection faces 812 are exposed in air. Therefore light beams impinging on the reflection faces 812 in air experience total reflection and are reflected to the light sensor 822. On the other hand, the light beam incident on the bottom-most reflection face 812′ is not reflected to the light sensor 822 but is refracted into the liquid 92. Thus, the circuit board 82 can determine the liquid level in the container based on reflected light beams received by the light sensor 822.
To obtain a precise light reflection path, the body 81 and the circuit board 82 are integrally formed together to ensure that the light incident on the reflection faces 812 can be totally reflected. Thus, the body 81 and the circuit board 82 are mounted in the container at the same time. When either the body 81 or the circuit board 82 fails, the entire detecting device 80 should be replaced with a new one.
If the body 81 and the circuit board 82 are separated from each other instead of integrally formed together, the accuracy of light reflection may be adversely affected because of the incorrect or improper alignment between the body 81 and the circuit board 82, thus causing level detecting error.
To overcome the shortcomings, the present invention provides a self-alignment filling level detecting device to mitigate or obviate the aforementioned problems.